A stent is an intravascular prosthesis implanted in a blood vessel to maintain vascular patency in an artery, vein, lymph, or another duct in the body such as the biliary duct, ureter, or urethera (collectively referred to as vessels). For example, a stent is often a necessary treatment for atherosclerosis. Atherosclerosis is an accumulation of lipids, also known as lesions, plaques, or atheromas, in the intimal or inner layer of an affected artery. The resulting intimal thickening of lipids restricts arterial blood flow, disrupting the function of or permanently damaging the nourished organ such as the heart. Typically, the accumulation of lipids is localized and occurs in coronary, renal, cerebral, or peripheral arteries.
Treatments for atherosclerosis focus on improving blood flow through narrowed arteries. One method, balloon angioplasty, simply expands a balloon catheter to compress lipid plaque against the artery wall. Unfortunately, scar tissue (neointimal proliferation) often builds up over time and renarrows the artery. This is called restenosis. To reduce the chance of restenosis, stents are often implanted. A stent is an expandable meshed metal tube used to support a narrowed artery after angioplasty. In this procedure, the stent is deployed at the center of the lipid accumulation. Once a deployment site is identified, the stent is maneuvered through the vessel to that site. Physicians typically use fluoroscopic x-ray and injection of radiopaque contrast and marking bands on the stent balloon to determine if the stent is positioned at the narrowed region. Once positioned, the stent expands to compress the lipids, thereby opening the artery and increasing blood flow. Stenting, as described in the prior art, significantly reduces restenosis of the artery compared to balloon angioplasty alone.
Ineffective and inaccurate stent placement can result in a poor overall patient outcome. For instance, if the stent is deployed too distal to the vessel narrowing, ineffective plaque compression can result. Further, a higher rate of restenosis can also be expected. If the stent is placed too proximal to a narrowing at the aorta origin (ostium), the stent cam hang into the aorta and a thrombus (clot) can form on the stent. Placement of the stent too proximal can also result in inappropriate and unintended blockage of another blood vessel.
Thus, an apparatus and method is needed to more effectively and accurately position a stent at a desired deployment site within the narrowed area of a vessel, thereby improving overall patient outcome.